Currently, climate change is causing sea and tide levels to rise which affects water levels on rivers, lakes, bays/coast areas; causing inundation and flooding on sea side and river side cities. Many large cities are located near rivers or within 100 km of the shore such as Bangkok, Houston, London, New York, Rotterdam, San Francisco, Saigon, Venice, etc. As a result, these cities are vulnerable to attack from high tide and/or storm surge. To solve these problems, infrastructure solutions such as dams or dikes are favored throughout the world, including Germany, Japan, Netherlands, United States, etc., or infrastructure solutions such as detention lakes or ponds, reforestation, etc. Each solution has its different advantages and disadvantages. These infrastructures are typically located at bay entrances, estuaries of major rivers or within the river.
To find a solution to the two types of high waves (i.e., tide and storm surge) discussed above, the challenge is to solve the large damaging potential on both scale and space of the waves. Previously, to counter wave damages, large scale infrastructure solutions such as dams, dikes and erect ground features through land leveling were typically implemented. The characteristics of such large scale solutions include extreme economic cost along with side issues of major landscape and surface modification, altering the nutritional exchanging processes of the zone (e.g., drainage) behind the protective structure. Such characteristics were only realized to be detrimental long afterwards and were consequently considered to be less than ideal, multiple regret solutions. This is a scientific conclusion from geographical regions utilizing solid infrastructures to counter sea level problems such as Japan, Netherlands, Thailand and the Eastern Northern European region neighboring Russia.
Existing dike systems often have flap gates to allow water vehicles to travel along the water body, creating the navigable channel. However, any major type of dike system when operating would require its flap gates to be closed, blocking the navigable channel. In storm situations, existing dike systems when operating would also require its flap gates to be closed to block out storm surges, blocking the navigable channel and forcing ships or water vehicles to dock along the shore. The economic damage from delayed transportation and direct storm damage is very high. The closed flap gates also prevent upstream water to discharge to the sea, causing upstream cities behind the existing dike systems to be inundated.
As described above, the construction of solid dikes are costly in terms of labor, materials, supplies, etc. Further, the navigable waterway is constricted since the wider the channel is built, the more materials would be required. Mega structures such as the dike systems with flap gates in the Netherlands are extremely expensive. The greatest disadvantage of this type of dike system is preventing the natural flow of water and hence, preventing the self-purification process of the water body inside the dike. Thus, this type of dike solution is often considered to be “less than ideal” and termed a “multi regret solution” by engineering experts.
Based upon these valuable experiences, the United Nations recently adopted a more “environmentally friendly” perspective in response to rising sea levels, emphasizing non infrastructure solutions mirroring nature (e.g., detention lakes or ponds, protective forests, etc.). The psychological benefits of these non-infrastructure solutions are superior; however, the disadvantages include high implementation cost, lengthy preparation time and ongoing pursuit of the plan's environmental perspective.
Thus, to meet the requirements of sustainable social development, another supplementary infrastructure solution must be prioritized to mitigate damage, namely, to life and property, as well as to the living and manufacturing environment.